Browsing by Author "Gordillo, F"

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    Electrophoretic karyotype of the filamentous fungus Penicillium purpurogenum and chromosomal location of several xylanolytic genes
    (2001) Chávez, R; Fierro, F; Gordillo, F; Martín, JF; Eyzaguirre, J
    The electrophoretic karyotype of the filamentous fungus Penicillium purpurogenum has been resolved. Using contour-clamped homogeneous electric field gel electrophoresis, five chromosomal bands were separated, with estimated sizes of 7.1, 5.2, 3.7, 2.9 and 2.3 Mbp, giving a total genome size of 21.2 Mbp. To our knowledge, this is the smallest Penicillium genome determined so far. By Southern blots and using homologous probes, the chromosomal location of five xylanolytic genes from P. purpurogenum was determined: axel (acetyl xylan esterase I), xynB (endoxylanase B) and abf1 (arabinofuranosidase 1) in chromosome I, xynA (endoxylanase A) in chromosome II, and axeII (acetyl xylan esterase II) in chromosome Ill. This is the first study where the location of xylanase genes in a Penicillium genome has been established. (C) 2001 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.
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    Histidine 140 plays a key role in the inhibitory modulation of the P2X4 nucleotide receptor by copper but not zinc
    (2003) Coddou, C; Morales, B; González, J; Grauso, M; Gordillo, F; Bull, P; Rassendren, F; Huidobro-Toro, JP
    To elucidate the role of extracellular histidines in the modulation of the rat P2X(4) receptor by trace metals, we generated single, double, and triple histidine mutants for residues 140, 241, and 286, replacing them with alanines. cDNAs for the wild-type and receptor mutants were expressed in Xenopus laevis oocytes and in human embryonic kidney 293 cells and examined by the two electrode and patch clamp techniques, respectively. Whereas copper inhibited concentration-dependently the ATP-gated currents in the wild-type and in the single or double H241A and H286A receptor mutants, all receptors containing H140A were insensitive to copper in both cell systems. The characteristic bell-shaped concentration-response curve of zinc observed in the wildtype receptor became sigmoid in both oocytes and human embryonic kidney cells expressing the H140A mutant; in these mutants, the zinc potentiation was 2.5-4-fold larger than in the wild-type. Results with the H140T and H140R mutants further support the importance of a histidine residue at this position. We conclude that His-140 is critical for the action of copper, indicating that this histidine residue, but not His-241 or His-286, forms part of the inhibitory allosteric metal-binding site of the P2X4 receptor, which is distinct from the putative zinc facilitator binding site.